So this crate:
Is made of those little pieces:
First, let me show you how the crate is organized in its tree
When the crate explodes, I'm creating a RigidBody2D per wood piece and throwing it away with speed. Then comes the messy part:
First, I get the wood piece, which is of Sprite type. Then I get the CollisionShape
D, which is only a proxy node for the GUI, but not really a type. Then I extract the real shape (rectangles in my case) and set them as collision shape of the newly created RigidBody2d. I haven't managed to set the shape directly to the rigidbody2d. Then remember that the RigidBody2d is created at coordinates (0,0) from its parent. Therefore to place it properly, we move the rigid body to the position of the sprite. Since the sprite becomes child of the rigid body I then set its position (relatively to its parent to (0,0)). I do the same for rotation. It's messy, but it's some kind of workaround.
I tried other things, and if anyone has suggestion to do it cleaner, I'm taking it!!!
And here the result: